Study on CMP Mechanism and Technology of Sapphire Substrate for Photo-conducting Device

Abstract

Sapphire(α-Al2O3) single crystals are widely used in many areas because of the special properties. As an important photoconducting device substrate material, stringent surface quality requirements are required. The use of CMP technique can produce high quality surface finishes at low cost and with fast material removal rates. In this paper, the polishing mechanism was studied. According to Arrhenius equation, temperature is the important factor of influencing chemical reaction rate. So the chosen temperature was 45°. SiO2 sol was chosen as abrasive, and the particle size is 40nm. For ensuring the stability of abrasive and chemical action of polishing slurry, the pH value was determined at 11.5~12. After polishing and cleaning the sapphire surface, the measured removal rate was above 11μm /h and the surface roughness was Ra 0.3nm. From the results, it was found that using such method, the optimal sapphire surface can be gotten.